This invention relates to a pesticide powder wherein the pesticide is released, in a metered fashion, over a prolonged period of time, and an effective method for using this powder.
The admixing of pure pesticides with inert powder for control of insects by subsequently spreading the mixture directly on the ground or by spreading from air-borne vehicles is known. A major disadvantage of admixing pesticide with "inert" powder is the care which must be taken to insure good mixing, particularly when using liquid pesticides, wherein loss of some volatile pesticides can occur. Further, these powders have good initial kill, but have little residual effect when subjected to rain or the flow of ground waters.
Other known systems of distributing pesticides include the spraying of water solutions thereof; the direct atomization of relatively undiluted pesticide in situ in very low volume; and thermal volatization and fuming of a mixture of the pesticide in a "fuel" oil to create a fog. The latter system requires pesticides which are thermally stable.
To obtain a residual effect, pesticides which have an inherent long-time persistence have been used. After many years of use some of these pesticides, such as D D T, are proving to be ecologically undesireable.
Another form of pesticides is illustrated in German Pat. No. 871,981. This patent describes a smoke or mist that is formed by reacting mist forming components which have dissolved therein a pest combating agent. This mist is applied directly to the air as it is formed. The reference fails to recognize that the mist can be collected and used for subsurface or subsequent application.